Lol what are you talking about? Many things can have a stem, such as a plant, which is not the same as the stem itself. According to all major dictionaries, stem can mean the main trunk of a plant, but it can also mean other certain plant part providing support. So your claim doesn’t hold.
Some definitions include the word “main”… and many definitions don’t. So actually I don’t see anything necessarily indicating that there can only be one stem.
Of course it can—why do you think something can’t have multiple stems? No one said that it stems exclusively from one thing.
It’s an interesting story, I definitely appreciate learning about this… and one which is very specific to Oklahoma, and doesn’t reveal all that much (nor would I say it’s necessary to hear to understand the crux) of Americanism.
No, we are taking about violence in a region, which can have many causes and origins. Violence in the region has stemmed from a combination of religion and foreign interference (and presumably many other things). If this isn’t what your claim addresses, then your claim is irrelevant to this conversation.